Conventionally, a known technology employs a magnetic sensor to detect a rotary angle of a motor. For example, Patent Document 1 discloses a configuration including two pairs of lead wires. In Patent Document 1, lead wires in the same phase are equipped centered on a magnetic sensor to be point symmetric to each other. In this way, the configuration cancels leakage of magnetic flux, which is caused by an electric current flowing in the lead wires, thereby to enhance detection accuracy of the rotary angle detected with the magnetic sensor.
(Patent Document 1)
Publication of unexamined Japanese patent application No. 2012-039737
Patent Document 1 may enable to cancel the influence of leakage of the magnetic flux caused by an electric current flowing in the lead wires. However, Patent Document 1 may not consider influence of a magnetic field from an external object outside the device.